1. Field of the Invention
This patent relates to a method of improving animal tissue quality. More specifically, this patent relates to a method of improving animal meat tissue quality by administering to the animal effective amounts of gamma-tocopherol.
2. Description of the Related Art
Consumers have become increasingly demanding of higher quality cuts of meat. For consumers, one major indicator of meat quality is visual appearance. With regard to beef, most consumers associate quality with the bright red color produced by the oxymyoglobin pigment. Unfortunately, oxymyoglobin is susceptible to oxidation. Within days of slaughter, oxygen exposure causes the oxymyoglobin to oxidize into metmyoglobin, turning the beef from bright red to a less appealing brownish color. Color is also important for pork with a reddish-pink color preferred. In addition, a key determinant of pork quality is the presence of exudate (“purge”) in the retail package resulting from the release of intracellular water due to protein denaturation and loss of cell wall integrity. Excessive purge results in economic loss to meat processors and a reduction in consumer value.
Research has shown that supplementing an animal's diet with antioxidants and, in particular, alpha-tocopherol acetate, can protect the slaughtered meat from oxidation, purge and discoloration. Consequently, meat producers may incorporate antioxidants into their animals' diets to increase the amount of antioxidants in the meat which, in turn, prolongs the shelf life of the meat.
Previous research indicates that supplementation of vitamin E in the form of alpha-tocopherol acetate at supranutritional levels is an effective means for improving meat quality (Faustman and Lynch, New Developments in Vitamin E Nutrition and Meat Quality, presented at Western Nutrition Conference, Saskatoon, Canada, 1998). In addition to improved color, supplementation of animal diet with alpha-tocopherol acetate results in improved stability of membrane bound lipids, maintenance of integrity of cellular membranes, and reduced purge (Monahan, F. J., et al., Food Chem. 1993).
Supranutritional vitamin E supplementation has been shown to be effective for turkeys and broilers (Marusich, et al., 1975), laying hens (Combs and Regenstein, 1980), veal calves (Igene, et al., 1976), horses (Yamauchi, et al., 1977), catfish (O'Keefe and Nobel, 1978), rainbow trout (Boggio, et al., 1985), swine (Asghar, et al., 1989), lambs (Strohecker, et al., 1997), and beef cattle (Faustman, et al., 1989). An extensive analysis of the benefits and mechanisms of vitamin E supranutritional supplementation is provided in Decker, E., Faustman, C. and Lopez-Bote, C., Antioxidants in Muscle Foods, John Wiley and Sons, Inc., 2000. Table 12-1 of Antioxidants in Muscle Foods contains a list of supranutritional vitamin E supplementation studies for various species, with effect, dosage and duration information noted, and Table 12-1 and the references cited therein are specifically incorporated by reference herein.
On a commercial scale, beef cattle feedlot nutritionists desire to achieve a total supplemental intake of vitamin E during the total feedlot period of about 50,000 IU/KG over a minimum of about 45 days. This can be accomplished with varying dosage levels and durations. For example, 500 IU/KG of vitamin E per steer daily for 126 days yielded this level (Liu, Q., et al., 1996, Titration of Fresh Meat Color Stability and Malondialdehyde Development with Holstein Steers Fed Vitamin E Supplemented Diets, J. Anim. Sci. 74:117–126), resulting in a total intake of 63,000 IU/KG and tissue level of 2.5 mg/g. Similarly, 1300 IU/KG of vitamin E per steer fed daily for 44 days resulted in a total intake of 57,200 IU/KG and a tissue level of 3.3 mg/g, while 400 IU/KG of vitamin E per steer fed daily for 180 days resulted in a total intake of 72,000 IU/KG and the same tissue level of 3.3 mg/g (Arnold, R., et al., 1993, Dietary a-Tocopherol Acetate Enhances Beef Quality in Holstein and Beef Bred Steers, J. Food Sci. 58:28–33). For exported beef, where storage times are longer, it is suggested that 2000 IU/KG of vitamin E per steer be fed daily for 100 days. This resulted in tissue levels of 6.1 mg/g (Sanders, S., et al., 1997, Vitamin E Supplementation of Cattle and Shelf-life of Beef for the Japanese Market, J. Anim. Sci. 2634–2640). Commercial supranutritional feeding levels of alpha-tocopherol for swine is approximately 200 IU/KG per animal on a daily basis for 100 days. This dosage level and duration may be varied to obtain a similar total intake as described for beef above.
While dietary supplementation with the antioxidant alpha-tocopherol has proven to be an effective means for improving meat quality, there remains a need to further improve meat quality.
Gamma-tocopherol has heretofore been known to be a weaker in vivo antioxidant than alpha-tocopherol. In vivo studies on iron-loaded rats have demonstrated the antioxidant efficacy of gamma-tocopherol to be about one-third that of alpha-tocopherol on a per unit mass basis as determined by their ability to inhibit lipid peroxidation (Dillard et al., 1983, Relative Antioxidant Effectiveness of Alpha-tocopherol and Gamma-tocopherol in Iron Loaded Rats, J. Nutr. 113: 2266–2273). It was also shown that gamma-tocopherol was not retained in the blood stream as well as alpha-tocopherol and suggested that the liver preferentially eliminates gamma-tocopherol, while alpha-tocopherol is transported to tissues via an alpha-tocopherol specific lipoprotein (Traber, et al., 1989, Preferential Incorporation of Alpha-tocopherol vs. Gamma-tocopherol in Human Lipoproteins, Am. J. Clin. Nutr. 49:517–526). It is also well known that only about 3–19% of gamma-tocopherol is absorbed in the bloodstream, as compared to about 100% of alpha-tocopherol (Lynch, G. L., et al., 1991, Vitamin E Structure and Bioavailability: Vitamin E in Animal Nutrition and Management, BASF Corp., Parsippany, N.Y., pp. 1–6). Additionally, certain in vitro studies have shown alpha-tocopherol to be a more effective antioxidant than beta, gamma and delta-tocopherol (See Burton, G., et al., 1981, Autoxidation of Biological Molecules: The Antioxidation Activity of Vitamin E and Related Chain-Breaking Phenolic Antioxidants in Vitro, J. Am. Chem. Soc. 103:6472–6477 and also Mukai, K., et al., 1987, Kinetic Studies of Antioxidant Activity of New Tocopherol Model Compounds in Solution, Bull. Chem. Soc. Jpn., 60:2163–2167). These articles, and the fact that gamma-tocopherol is a biological precursor to alpha-tocopherol, have led those of skill in the art to believe that gamma-tocopherol is less effective than alpha-tocopherol in improving meat quality. In fact, despite extensive analysis of alpha-tocopherol in feeding studies, the effect of dietary gamma-tocopherol supplementation on tissue quality, such as meat, has not been evaluated in feeding studies.
Thus it is an object of the present invention to provide a method for improving the tissue quality of an animal. It is a further object to improve meat tissue, especially its water-holding capacity (as estimated from pH) and its shelf life (as measured by color change and lipid peroxidation as measured by and change of TBA number over time).
Another object of the present invention is to provide a method for improving tissue quality over that already achieved through diet supplementation with alpha-tocopherol.
Further and additional objects will appear from the description and appended claims.